Pigeons are smart enough to read, study finds

For decades, the term “bird brain” has been used to refer to a person of lower intelligence, but a new study appearing this week in the Proceedings of the National Academy of Sciences (PNAS) suggests this term might not be appropriate.

In their new PNAS paper, University of Otago psychologist Dr. Damian Scarf and his colleagues revealed that pigeons were capable of distinguishing actual words from non-words by processing letter combinations visually, performing these tasks just as well as baboons.

According to Dr. Scarf’s team, this is the first study of its kind to identify a non-primate species as possessing “orthographic” abilities, meaning that they possess at least some of the conventions (spelling, capitalization, word breaks, punctuation, etc.) required for writing a language.

“A novel theory suggests that orthographic processing is the product of neuronal recycling, with visual circuits that evolved to code visual objects now co-opted to code words,” the study authors wrote. “We provide a litmus test of this theory by assessing whether pigeons, an organism with a visual system organizationally distinct from that of primates, code words orthographically.”

They added that the pigeons “not only correctly identified novel words” but also displayed “the hallmarks of orthographic processing, in that they are sensitive to the bigram frequencies of words, the orthographic similarity between words and non-words, and the transposition of letters. These findings demonstrate that visual systems neither genetically nor organizationally similar to humans can be recycled to represent the orthographic code that defines words.”

Birds’ success rate was ‘significantly’ better than simple luck

As part of the research team’s experiments, a quartet of pigeons were taught to peck out four-letter words in English as they appeared on a screen, or to peck a symbol when they saw a four-letter non-word appear. Additional words were added, one at a time, until each of the birds had accumulated vocabularies of 26 to 58 words and more than 8,000 nonwords.

Next, the researchers tested the pigeons to ensure that they were actually learning to tell words from non-words (instead of simply memorizing them) by introducing them to a never-before-seen group of words. The birds identified these new words at a rate “significantly above chance,” the researchers said Monday in a statement.

Dr. Scarf explained that the birds likely accomplished this feat by determining whether there was a greater chance statistically that specific two-letter pairs known as bigrams (such as EN and AL) were more likely to be associated with words or non-words. Essentially, the birds looked at letter pairs and determined whether or not each set commonly reappeared in actual words.

The findings, co-author Onur Güntürkün from Ruhr University in Germany, demonstrates that “pigeons – separated by 300 million years of evolution from humans and having vastly different brain architectures – show such a skill as orthographic processing is astonishing.” His colleague, Otago University Professor Michael Colombo, added that “we may have to seriously re-think the use of the term ‘bird brain’ as a put down.”

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Image credit: Thinkstock

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